In the conventional methods of developing light-sensitive materials, there are typically such a disposing method that the waste is taken over by traders for the recovery of waste materials or a waste solution disposal facility for treating the waste is built with large investment, which leads to problems in cost and space for the disposal of the waste.
Especially, for the purpose of making the process of the waste produced during treatment of silver halide photographic materials easy, a device for the evaporation to dryness of the waste by heating to evaporate water is disclosed in Japanese Utility Model Publication Open to Public Inspection No. 70841/1985 (Hereinafter referred to as Japanese Utility Model O.P.I. Publication), however, because the waste is directly condensed or evaporated to dryness and, particularly, when the processing waste solution of non-silver halide light-sensitive materials include a lot of high molecular ingredients, solid matter (including sludge) will stick to the wall in an evaporation vessel or to a heat source. This result in lower efficiency in evaporation process, troublesome maintenance for eliminating the solid matter or sludge, and difficulty in removing the sludge.